Mining of sulfur using spaced-apart wells



MINING OF SULFUR USING SPACED-APART WELLS Filed Sept. 26, 1956 Oct. 1,1957 c. L. PROKOP ETAL 2 Sheets-Sheet 1 l lll FIG. 2.

MELTED SULFUR R SIT I5 MELTED SULFUR 28 MELTED SULFUR SULFU DEPOINVENTORS. Charles L. Prokop, Gilbert 6. Wrighfsman, Wilmer A. Hoyer,Millard S. Taggarr,Jr.,

SULFUR DEPOSIT c. L. PROKOP EI'AL 2,808,248

MINING OF SULFUR USING SPACED-APART WELLS 2 Sheets-Sheet 2 GOMBUSTIBLEMIXTURE 40JJ SPA PL BURNER ASSEMBLY SULFUR DEPOSIT 5 umn 4 O 2 4 2\ Y 43Q 1 1|: lvl F 4 I 1| ll Lr' b Iv ll ll 8 2 1 L L P 3 w by M w W 2 2 2 22 ww m n m E O 2 wm 2 2 w l i I- all '1 k M f 2 5 a 6 7 I 3 v 4 Fn2. .l2 2 2 Oct. 1, 1957 Filed Sept. 26, 1956 SULFUR INVENTORS. Charles L.Prokop, Gilbert G. Wrighlsman, Wilmer A. Hoyer, Millard S. Taggart,Jr.,

Ala;

ATTORNEY.

United State MINING OF SULFUR USING SPACED-APART WELLS Charles L. Prokopand Gilbert G. Wrightsman, Houston, Wilmer A. Hoyer, Bellaire, andMillard S. Taggart, Jr., Houston, Tex., assignors to Humble Oil &Refining Company Application September 26, 1956, Serial No. 612,329

Claims. (Cl. 262-3) The present invention is directed to a method formining sulfur. More particularly, the invention is directed to themining of sulfur from a sulfur deposit penetrated by spaced-apart wells.In its more specific aspects, the invention is concerned with a methodfor mining sulfur in which the sulfur deposit is progressively depletedof sulfur.

The present invention may be briefly described as a method for miningsulfur from an underground formation containing a sulfur deposit, thesulfur deposit being penetrated by at least two spaced-apart wells. Thefirst of said wells penetrates the sulfur deposit above the level wherethe sulfur deposit is penetrated by a second of the wells. Hot gas isintroduced into the first of said wells at a temperature sufficientlygreat to melt the sulfur in the deposit, the hot gas being underpressure sufficiently high to cause or force the gas to travel from thefirst well to the second well. Water and gas are produced from thesecond well and melted sulfur is produced from at least the first well.The hot gas dis. places formation water and sulfur and provides anexpanding gas cap in the formation whereby the formation isprogressively depleted of sulfur from the highest elevation in theformation to the lowest elevation in the formation.

The gases employed in the practice of the present invention may suitablybe flue gases such as generated by burning a mixture of natural gasessuch as produced from subsurface formations. The flue gas may begenerated at the Well head or adjacent thereto or it may be generated byan underground combustion near the sulfur deposit as may be desired. Theflue gas may be generated by a submerged combustion in a pool of watersuch as sea water or brackish or saline water or the flue gas may bemixed with the brackish or saline water in a spray such thatthetemperature of the water is raised by the combustion operation.

A suitable burner for use in burning natural gas underground andadjacent the sulfur deposit in the Well is described in the patent toKaasa, U. S. 2,722,278, issued November 1, 1955. Other suitable burnersfor underground combustion are exemplified by the patent to Piros et211., U. S. 2,668,592, issued February 9, 1954.

Generation of the flue gas by combustion at the earths surface may beillustrated by the method and apparatus described in the Brogdon patent,2,756,029, issued July 24,1956, and the Axelrad et al. patent,2,756,035, issued July 24, 1956, wherein the mine water is heated by theflue gas, both of which may be used in the practice of the presentinvention.

The hot flue gases may be introduced into the sulfur deposit at atemperature in the range of about 240 F. to about 320 F. and at apressure in the range from about 0.4 to about 1.0 p. s. i. g. per footdepth of burial of. the sulfur deposit such that the sulfur in thesulfur depositis melted by contact with the hot gases and such Ice thatthe pressure is suflicient to cause the gas to travel from the firstwell to the second well.

Melted sulfur and water may be produced from the first and second wellswhile the hot flue gas is introduced only into the first well. The hotgases are suitably introduced into the upper half of the sulfur depositat a temperature in the range given before either as a gaseous mixtureor in admixture with or carried by hot water introduced from the wellhead. The hot water may be introduced into the well after a period oftime which will be governed by the sulfur being progressively depletedfrom the formation adjacent the first well. By injecting hot water andhot flue gas after the sulfur deposit has been depleted adjacent thefirst well, the formation is progressively depleted by means of theexpanding gas cap causing the injected water to deplete the formationprogressively from top to bottom while gas and water travel to thesecond well. At this stage sulfur will be produced from both wells.

The present invention will be further illustrated by reference to thedrawing in which Fig. 1 is a schematic view of a well head arranged on aplatform over a sulfur deposit in a marine location;

Figs. 2 through 4 represent a .stagewise showing of the progressivedepletion of sulfur from a sulfur-bearing formation;

Fig. 5 represents a showing of apparatus wherein the hot flue gas isgenerated at the well head; and

Fig. 6 illustrates apparatus for use with the present invention wherethe hot flue gas is generated in the well.

Referring now to the drawing in which identical numerals may be employedto designate identical parts, numeral 11 designates an offshore platformsupported on suitable pilings such as 12 penetrating the sea bottom 13below a body of water 14. The body of water 14 may suitably be a body ofwater adjacent the continental shores of the United States or it may bea lake bottom or a stream bottom.

Drilled to penetrate the sea bottom 13 and a sulfurbearing formation 15is a well 16 into which an air or gas line 17 is arranged. The line 17islconnected to an air compressor 18 and to a gas engine 19. The gasengine 19 may suitably be only the flue gas generator or an auxiliarygas burner may be desired. The air compressor 18 and gas engine 19 aresuitably arranged on the platform 11. The gas burner may be located onthe platform, at the well head, or in the well casing near the sulfurdeposit.

Referring now to Figs. 2 through 4, the line 17a, through which thegases are injected, may suitably connect to the outer string 17 of theWell 16 in which is arranged an inner string 20 which provides anannulus 21 between the outer string 17 and the inner string 20. Arrangedwithin the inner string 20 is a second inner string 22 which provides anannulus 23 between the first inner string 20 and the second inner string22.

The outer string 16 is perforated in the sulfur deposit 15 to provideperforations 24 and is further perforated in the sulfur deposit 15 toform second perforations 25, the two perforations being separated fromeach other by a packing means 26.

The foregoing description applies to well A which is arrangedup-formation in the sulfur deposit 15 from well B which is arrangeddown-formation penetrating the sulfur deposit 15 from the well A. Thewell B is comprised of similar and identical parts to well A which areidentified by identical numerals for the purpose of simplicity.

In the first stage of the present invention, as illustrated by Fig. 2,natural gas is burned at the well head or in the casing near the sulfurdeposit 15 to introduce the combustion products through the annulus 21and thence through perforation 24 to provide an expanding gas cap 27inthe sulfur deposit 15. As stated, this combustion may be conducted inthe bottom of the well or adjacent the well in the formation 15. Theheat contained in the flue gas which may be at a temperature of 240 to320 F. causes the sulfur 28in the sulfur deposit 15 to be displaced asshown by the arrows to the wellA- with the formation water generallyindicated by the numeral 29 being caused to migrate to the well B andenter the well B through the perforations 24a and 25a therein and causedto flow upwardly therein through the annulus 2.1a and the annulus 23a.The sulfur is recovered up the Well 16 through the annulus 23 and as theoperation proceeds the sulfur may also be recovered up the annulus 23afrom well B. Hot sea Water may be introduced simultaneously into thewell A through the annulus 21 to cause a substantial'flooding andheating of the sulfur deposit 15 by the heated sea water and the hotgases. The gas cap 27 is maintained in the sulfur formation 15 toprovide an expanding gas cap which forces the hot water, whetherformation or injected water, to sweep the lower part of the formation 15down-formation from well A such that the sulfur is progressivelydepleted from the formation 15.

In short, in Fig. 2 of the drawing the natural gas is burned at the wellhead as desired and injected as shown into the upper one-half of thesulfur formation or stratum 15. The injection temperatures may becontrolled by controlling the amount of gas and air compressed or burnedprior to injection through the well A. The sulfur may be produced fromthe well A by lift provided by the hot injected gases or by auxiliarylift provided by injecting hot gas or air down the secondin-ner string22.

=The formation water is produced as described from thewell B and gascommunication is provided between the wells A and B.

In the second stage of the present invention, as shown in Fig. 3, theinjection of hot gases is continued through well A and the production ofsulfur 28 is also continued from well A with formation water and gasesbeing withdrawn from the well B through the annulus 21a and through theannulus 23a with sulfur also being produced through the annulus 23a.Gases may be injected into the well 3 through the innermost string 22aas is desired.

In the third stage of the operation of the present invention, hot watersuch as hot sea water or hot fresh water is introduced into the well Adown the annulus 23 along with hot gases also introduced down theannulus 23. In

troduction of hot gas is continued down the annulus 21 with the hot gasbeing forced into the gas cap'li and the hot water flowing under the gascap 27 toward the well 8. In this stage of the operation it will benoted that the sulfur 28 has been substantially completely depleted fromthe formation 15 adjacent the Well A and the expanding gas cap iscausing the hot water, either formation water or injected hot water, toprogressively deplete the sulfur from the deposit 15 from up'forma tionto down-formation. In this stage of the operation, sulfur 28 isrecovered only from the second 'well with gas being bled off in asutlicient amount to maintain the expanding gas cap 27 and to maintainthe water in contact with that portion of the formation which had notbeen depleted of its sulfur content. A sutficient amount of hot water isrecovered with the sulfur and gases through the annulus 230 while thegases, such as are withdrawn otherwise, are withdrawn through theannulus 21a of well B.

Referring now to Fig. 5, a burner assembly 30 is connected into line17a. The burner'assembly 30 is pro vided with a spark plug 31 having anelectrical connection 32 connecting the spark plug 31 to a source ofeleclines 37 and 38, by way of which gas and air are introduced intoline 36. A combustible mixture of about one part of fuel gas, such asnatural gas, methane, ethane, propane and the like, and nine parts ofair is introduced into line 36 and ignited in the burner assembly 30 andburner 34 by energizing the spark plug 31. The hot flue gas so generatedis then conducted down the pipe 17 as has been described with referenceto Figs. 1 to 4.

Referring now to Fig. 6, an arrangement is provided whereby a mixture offuel gas and air is burned in the well adjacent the sulfur deposit toform the hot gases. In the apparatus of Fig. 6, there is arranged in theannulus 21 a first pipe or conduit 40, which terminates in a burnerassembly 41, provided with slots 42. Also connected to the burnerassembly adjacent the opening 43 is a second pipe or conduit 44, whichterminates at the well head and which has a spark plug 31 arrangedtherein connected to a source of electrical energy, not shown, byelectrical connecting means 32.. A combustible mixture of about one partof fuel gas and about nine parts of air is introduced through the pipes40 and 44 leading into the burner 41; a supply of air is also introducedinto the annulus 21 by way of line 45. By energizing the spark plug 31in line 44, the combustible mixture in the burner 41 is ignited to causegeneration of flue gas at an elevated temperature adjacent the sulfurdeposit 15 and for introduction thereinto.

' The operation with respect to Fig. 6 is in accordance with the.operation described with reference to Figs. 1 to 4, inclusive.

It will be seen from the foregoing description taken with the drawingthat the present invention is of .considerable advantage and utility inthat combustion of gases and heated gases provide a source of heat forthe mining of sulfur with a minimum utilization of hot water. Heretoforeit was necessaryto introduce from about 2000 to about 8000 gallons ofheated water for every ton of sulfur mined Whereas in. the presentinvention this may suitably be reduced to about 600 gallons per ton ofmined sulfur. In addition, equipment outlays are reduced, heat lossesareminimized, sulfur production is increased over that possibleheretofore and as a result economical operation is provided. In short,the invention provides a new and useful mode of producing sulfur inwhich hot gases supply a substantial amount of heat for mining thesulfur.

While hot flue gases have been illustrated as the type of gaseousmaterial, other gases such as heated air, heated nitrogen and othersuitable gaseous fluids may be used. For example, hot natural gas suchas methane, ethane or propanemay be used with the depleted formationultimately forming storage capacity for the heated hydrocarbonused'to'niine the sulfur. i

The nature and objects of the present invention having been completelydescribed and illustrated, what we wish to claim as new and useful andto'secure by Letters Patent is:

1. A method for mining sulfur from an underground formation containing asulfur deposit penetrated by at least two spaced-apart wells withthe-first of said wells penetrating said sulfur deposit at 'a levelabove the level where said sulfur deposit is penetrated by a second ofsaid wells which comprises introducing hot gas into the first of saidwells at a. temperature suflicient to melt sulfur in said deposit and ata pressure suflicient to cause said gas to travel to the second of saidwells, producing water and gas from the second well and producing meltedsulfur from at least the first well, said hot gas displacing formationwater and providing an expanding gas cap in said formation whereby saiddeposit is progressively depleted of sulfur. from the, highest elevationin said formation to the lowest elevation in said formation.

2. A method for mining sulfur from'an underground formation containing asulfur deposit penetrated by at least two spaced-apart wells with thefirst of said-wells penetrating said sulfur deposit at a level above thelevel where said sulfur deposit is penetrated by a second of said wellswhich comprises introducing =hot flue gas into the first of said wellsat a temperature suflicient to melt sulfur in said deposit and at apressure sufiicient to cause said gas to travel to the second of saidwells, producing water and gas from the second well and producing meltedsulfur from at least the first well, said hot gas displacing formationwater and providing an expanding gas cap in said formation whereby saiddeposit is progressively depleted of sulfur from the highest elevationin said formation to the lowest elevation in said formation.

3. A method in accordance with claim 1 in which the hot flue gas isgenerated at the well head of said first well.

4. A method in accordance with claim 1 in which the hot flue gas isgenerated by combustion in the sulfur deposit.

5. A method for mining sulfur from an underground formation containing asulfur deposit penetrated by at least two spaced-apart wells with thefirst of said wells penetrating said sulfur deposit at a level above thelevel where said sulfur deposit is penetrated by a second of' said wellswhich comprises introducing hot gas into the first of said wells at atemperature sufiicient to melt sulfur in said deposit and at a pressuresuflicient to cause said hot gas to travel to the second of said wells,producing gas from the second well and producing melted sulfur and waterfrom the first and second wells, said hot gas displacing formation waterand providing an expanding gas cap in said formation whereby saiddeposit is progressively depleted of sulfur from the highest elevationin said formation to the lowest elevation in said formation.

6. A method for mining sulfur from an underground formation containing asulfur deposit penetrated by at least two spaced-apart wells with thefirst of said wells penetrating said sulfur deposit at a level above thelevel where said sulfur deposit is penetrated by a second of said wellswhich comprises introducing hot gas and hot water into the first of saidwells at a temperature suflicient to melt sulfur in said deposit and ata pressure sufiicient to cause said gas to travel to the second of saidwells, producing water and gas from the second well and producing meltedsulfur from the first and second wells, said hot gas displacingformation water and providing an expanding gas cap in said formationwhereby said deposit is progressively depleted of sulfur from thehighest elevation in said formation to the lowest elevation in saidformation.

7. A method in accordance with claim 6 in which the hot water is heatedsea water.

8. A method for mining sulfur from an underground formation containing asulfur deposit penetrated by at least two spaced-apart wells with thefirst of said wells penetrating said sulfur deposit at a level above thelevel where said sulfur deposit is penetrated by a second of said Wellswhich comprises introducing hot gas through the first of said wells intothe upper half of said deposit at a temperature sufficient to meltsulfur in said deposit and at a pressure suflicient to cause said gas totravel to the second of said wells, producing'water and gas from thesecond well and producing melted sulfur from at least the first well,said hot gas displacing formation water and providing an expanding gascap in said formation whereby said deposit is progressively depleted ofsulfur from the highest elevation in said formation to the lowestelevation in said formation.

9. A method in accordance with claim 8 in which hot water at asufficient temperature to melt the sulfur is introduced with said hotgas.

10. A method for mining sulfur from an underground formation containinga sulfur deposit penetrated by at least two spaced-apart wells with thefirst-of said wells penetrating said sulfur deposit at a level above thelevel where said sulfur deposit is penetrated by a second of said wellswhich comprises introducing hot gas into the first of said wells at atemperature sufficient to melt sulfur in said deposit and at a pressuresufficient to cause said gas to travel to the second of said wells,producing water from the first and second wells, producing melted sulfurfrom at least the first well, said hot gas displacing formation waterand providing an expanding gas cap in said formation whereby said"deposit is progressively depleted of sulfur from the highest elevationin said formation to the lowest elevation in said formation, andthereafter injecting hot water along with the hot gas into the firstwell whereby sulfur is produced from the first and second wells.

References Cited in the file of this patent UNITED STATES PATENTS581,479 Higgins et al. Apr. 27, 1897

1. A METHOD FOR MINING SULFUR FROM AN UNDERGROUND FORMATION CONTAINING ASULFUR DEPOSIT PENETRATED BY AT LEAST TWO SPACED-APART WELLS WITH THEFIRST OF SAID WELLS PENETRATING SAID SULFUR DEPOSIT AT A LEVEL ABOVE THELEVEL WHERE SAID SULFUR DEPOSIT IS PENETRATED BY A SECOND OF SAID WELLSWHICH COMPRISES INTRODUCING HOT GAS INTO THE FIRST OF SAID WELLS AT ATEMPERATURE SUFFICIENT TO MELT SULFUR IN SAID DEPOSIT AND AT A PRESSURESUFFICIENT TO CAUSE SAID GAS TO TRAVEL TO THE SECOND OF SAID WELLS,PRODUCING WATER AND GAS FROM THE SECOND WELL AND PRODUCING MELTED SULFURFROM AT LEAST THE FIRST WELL, SAID HOT GAS DISPLACING FORMATION WATERAND PROVIDING AN EXPANDING GAS CAP IN SAID FORMATION WHEREBY SAIDDEPOSIT IS PROGRESSIVELY DEPLETED OF SULFUR FROM THE HIGHEST ELEVATIONIN SAID FORMATION TO THE LOWEST ELEVATION IN SAID FORMATION.